function toggle(div_id) {
                var el = document.getElementById(div_id);
                if ( el.style.display == 'none' ) {  el.style.display = 'block';}
                else {el.style.display = 'none';}
}
function blanket_size(popUpDivVar) {
                if (typeof window.innerWidth != 'undefined') {
                                viewportheight = window.innerHeight;
                } else {
                                viewportheight = document.documentElement.clientHeight;
                }
                if ((viewportheight > document.body.parentNode.scrollHeight) && (viewportheight > document.body.parentNode.clientHeight)) {
                                blanket_height = viewportheight;
                } else {
                                if (document.body.parentNode.clientHeight > document.body.parentNode.scrollHeight) {
                                                blanket_height = document.body.parentNode.clientHeight;
                                } else {
                                                blanket_height = document.body.parentNode.scrollHeight;
                                }
                }
                var blanket = document.getElementById('blanket');
                blanket.style.height = blanket_height + 'px';
                var popUpDiv = document.getElementById(popUpDivVar);
                popUpDiv_height=blanket_height/2-150;//150 is half popup's height
                popUpDiv.style.top = popUpDiv_height + 'px';
}
function window_pos(popUpDivVar) {
                if (typeof window.innerWidth != 'undefined') {
                                viewportwidth = window.innerHeight;
                } else {
                                viewportwidth = document.documentElement.clientHeight;
                }
                if ((viewportwidth > document.body.parentNode.scrollWidth) && (viewportwidth > document.body.parentNode.clientWidth)) {
                                window_width = viewportwidth;
                } else {
                                if (document.body.parentNode.clientWidth > document.body.parentNode.scrollWidth) {
                                                window_width = document.body.parentNode.clientWidth;
                                } else {
                                                window_width = document.body.parentNode.scrollWidth;
                                }
                }
                var popUpDiv = document.getElementById(popUpDivVar);
                window_width=window_width/2-150;//150 is half popup's width
                popUpDiv.style.left = window_width + 'px';
}
function popup(windowname) {
    blanket_size(windowname);
                window_pos(windowname);
                toggle('blanket');
                toggle(windowname);  
}


